This latest subgenre in the long history of art/pop hybridisation is different and new. It's not just another example of the mutual seduction of pop and art that goes back to Peter Blake and Richard Hamilton designing Beatles album covers. For one thing, these artists are participating directly in music – making it or dancing in public to it. For another, and this makes them different from the legions of young artists who are in arty bands, they are mature people, stepping into mainstream pop. Abramović is in her late 60s, Ai Weiwei well into his 50s. Yoko Ono, one half of art and pop's ultimate marriage, is 80.

Is their embrace of mainstream pop music a symptom of the same disintegration of age boundaries the Rolling Stones enacted at Glastonbury? Surely, this is a truly definitive time in the story of modern culture.

Since 1950 the most important and powerful phenomenon in cultural history has been the blurring, even dissolution, of boundaries between high and low. Those divisions have long since virtually vanished but one barrier remained: that of youth and age – a barrier created by the very rise of pop after the second world war. Pop was, until now, "youth culture".

Its fans and makers aged, but that myth of youth lived on. Until now. For the first time, age literally doesn't matter. Artists often see what is happening before it happens (as can Mick Jagger, apparently). Today, these artists are asserting that pop culture now belongs to everyone and unites the world, beyond all categories – including age.